In Ruby, \A and \z denote the beginning and end of a string, regardless
of if those strings contain newlines -- like using /s in Perl.
^ and $ match the start and end of any line of a string - like /m in
Perl.
Also, with those zip code validations, you'll reject valid zip codes
from other nearby countries like Canada.
Merge pull request #7 from joealba/regex_fix

In Ruby, \A and \z denote the beginning and end of a string, regardless of if those strings contain newlines -- like using /s in Perl. ^ and $ match the start and end of any line of a string - like /m in Perl. Also, with those zip code validations, you'll